This invention relates to the field of nuclear medicine. More particularly, this invention relates to an apparatus and to an associated method for detecting sources of radioactivity inside a patient for diagnostic purposes.
xe2x80x9cNuclear medicinexe2x80x9d refers in part to that branch of the medical field which uses various types of radioactive isotopes to detect internal organic and histological defects in a patient. Generally, a chemical composition incorporating a radioactive isotope is injected or otherwise administered to a patient and, after a sufficient period to allow absorption of the composition by target tissues, the patient is scanned to detect whether and to what extent the chemical composition has been absorbed. For example, in determining whether a person has a tumor of the thyroid, radioactive potassium iodide is administered to the person and, after the lapse of a predetermined migration and absorption period, the person is positioned on a table below a detector tuned to sense radioactive emissions of the iodide isotope.
A problem with conventional nuclear medicine procedures is the high mortality rate. More specifically, because the patients subjected to such diagnostic procedures are very ill, and because the technicians operating the nuclear medicine equipment are not trained as doctors, many patients die during the testing procedures.
An object of the present invention is to provide an apparatus for detecting radioactive isotopes in a patient.
Another object of the present invention is to provide such an apparatus which is of reduced size relative to conventional nuclear medicine detectors.
A more particular object of the present invention is to provide such an apparatus which is portable.
It is another particular object of the present invention to provide such an apparatus which is capable of being used in an intensive care unit of a hospital facility.
It is an additional object of the present invention to provide an associated nuclear medicine diagnostic method.
These and other objects of the present invention will be apparent from the drawings and descriptions herein.
A medical diagnostic apparatus comprises, in accordance with the present invention, a carrier body, a plurality of rigid substrates each bearing at least one solid-state gamma ray sensor, the substrates being attached to the carrier body, and a computer operatively connected to the sensors for receiving signals therefrom and deriving information about location and size of a source of radioactivity in the patient. The carrier body enables disposition of different gamma ray sensors on different sides of the patient so that the sensors at least partially surround the patient.
In accordance with a main embodiment of the present invention, the carrier body is flexible and substantially conformable to a patient. The carrier body may specifically take the. form of a flexible web which may be wrapped around a patient in a generally cylindrical configuration having a diameter which depends on the size of the particular portion of a patient which is being investigated via radioactive tagging.
Generally, as in conventional nuclear medicine investigations, the patient is supplied with a radioactive composition which is keyed for take-up or absorption by a particular organ of the body. In this case, the mere detection of a source in the body indicates that the target zone or organ has absorbed the composition. The target zone, and hence the location of the radioactive source (target tissues), is known before hand. The extent of the absorption may be measured by the medical diagnostic apparatus of the present invention.
A medical diagnostic system in accordance with the present invention may also be used for determining the shape, size, and location of an organic tissue body which has absorbed or acquired a radioactively tagged composition. In that case, it is advantageous to know the positions of the various solid-state gamma ray sensors relative to one another upon juxtaposition of the carrier body to the patient. These positions will be known as a matter of course if the carrier body is rigid. A rigid carrier body may take a semicylindrical form, such as a slotted collar or sleeve. Alternatively, where the carrier body is flexible or otherwise internally shiftable, an active sensing system may be provided for enabling determination of the positions of the gamma ray sensors relative to one another and relative to the patient. Generally, this sensing system is operatively connected to the computer for providing position information thereto. The computer itself is programmed to determine relative positions of the gamma ray sensors from the incoming position information.
Where the shape and size of a source of radioactive emissions is determinable as disclosed herein, the location of a source of radioactivity in a patient may be determined by comparing the detected shape and size of the source with the shapes and sizes of expected target zones or organs.
In the case of a flexible or internally movable carrier body, the position sensing system may be optical. For example, interferometric metrology devices may be attached to substrates of the gamma ray sensors for measuring changes in positions of adjacent sensors. Alternatively, the carrier body may be illuminated with an optical grid which is distorted due to the irregular surfaces of the carrier body and the patient. An image captured by one or more cameras is analyzed by computer to determine the shape causing the distortions in the apparent shape of the optically generated grid.
A related medical diagnostic device comprises, in accordance with the present invention, a plurality of solid-state radioactivity sensors and a carrier attached to the sensors for enabling disposition of the sensors in a nonplanar configuration so as to at least partially surround a portion of a patient.
In accordance with another feature of the present invention, the carrier specifically takes the form of at least one movable connector element attached to the sensors for movably coupling the sensors to one another. The sensors may be movably attached to one another so as to allow at least a pivoting motion of each sensor relatively to a respective one other of the sensors. In a particular embodiment of the present invention, the connector element is a flexible substrate or web conformable to a skin surface of a patient, the sensors being attached in a predetermined array to the flexible substrate.
The sensors have output leads operatively connected to a computer programmed to derive information about location and size of a source of radioactivity in the patient.
An associated medical diagnostic method comprises, in accordance with the present invention, administering to a patient a chemical composition containing a radioactive isotope, thereafter disposing about the patient a plurality of solid-state sensors sensitive to gamma rays generated by radioactive decay of the isotope, conducting signals from the sensors to a computer, and operating the computer to derive information about location and size of a source of radioactivity in the patient.
Pursuant to a feature of the present invention, at least two of the sensors are positioned on different sides of the patient. Ideally, the sensors are distributed so as to surround the patient. The sensors may be placed in essential contact with the patient, for example, where the sensors are attached to a flexible web which is manipulated to conform to the patient.
The present invention provides an apparatus useful in medical diagnostic procedures and more particularly useful in medical diagnostic procedures wherein radioactive isotopes are administered to a patient.
The apparatus of the present invention is of reduced size relative to conventional nuclear medicine detectors. More specifically, an apparatus in accordance with the present invention may be designed for portability.
An apparatus and an associated method in accordance with the present invention are capable of being used in an intensive care unit of a hospital facility.